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  <title>Document</title>
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<body>
  <script>
    let arr = [2, 6, 1, 7, 4]
    // 1. 求和的变量 sum
    let sum = 0
    // 2.遍历累加
    for (let i = 0; i < arr.length; i++) {
      // console.log(arr[i])
      // sum = sum + arr[i]
      sum += arr[i]
    }
    console.log(`数组的和的结果是: ${sum}`)
    // 3. 平均值  和 / arr.length  = 4
    console.log(`数组的平均值结果是: ${sum / arr.length}`)


    // sum = sum + arr[0]
    // console.log(sum) 
  </script>
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